With the advancement of science and technology, fluid transportation devices used in many sectors such as pharmaceutical industries, computer techniques, printing industries or energy industries are developed toward elaboration and miniaturization. The fluid transportation devices are important components that are used in for example micro pumps, micro atomizers, printheads or industrial printers. Therefore, it is important to provide an improved structure of the fluid transportation device.
For example, in the pharmaceutical industries, pneumatic devices or pneumatic machines use motors or pressure valves to transfer gases. However, due to the volume limitations of the motors and the pressure valves, the pneumatic devices or the pneumatic machines are bulky in volume. In other words, the conventional pneumatic device fails to meet the miniaturization requirement, and is not suitable to be installed in or cooperated with portable equipment. Moreover, during operations of the motor or the pressure valve, annoying noise is readily generated.
Therefore, it is important to provide a fluid control device with small, miniature, silent, portable and comfortable benefits in order to eliminate the above drawbacks.
FIG. 1 is a schematic cross-sectional view illustrating a fluid control device. The fluid control device comprises a housing 1, a piezoelectric actuator 2, a first insulation plate 3a, a conducting plate 4 and a second insulation plate 3b. The housing 1 comprises an outlet plate 11 and a base 12.
The outlet plate 11 comprises a sidewall 111 and a bottom plate 112. The sidewall 111 is protruded from the edges of the bottom plate 112. Moreover, an accommodation space 113 is defined by the sidewall 111 and the bottom plate 112 collaboratively. The piezoelectric actuator 2 is disposed within the accommodation space 113. A temporary storage chamber 114 is concavely formed on a surface of the bottom plate 112 for temporarily storing the fluid. At least one exit 115 penetrates through the bottom plate 112. The exit 115 is in communication with the temporary storage chamber 114.
The base 12 comprises an inlet plate 121 and a resonance plate 122. The inlet plate 121 comprises at least one inlet 1211, at least one convergence channel 1212 and a convergence chamber 1213. A first end of the at least one convergence channel 1212 is in communication with the inlet 1211. A second end of the at least one convergence channel 1212 is in communication with the convergence chamber 1213. The convergence chamber 1213 is used for temporarily storing the fluid. Moreover, the depth of the convergence chamber 1213 and the depth of the at least one convergence channel 1212 are equal. The resonance plate 122 is made of flexible material. The resonance plate 122 comprises a central aperture 1223 corresponding to the convergence chamber 1213 of the inlet plate 121. Consequently, the fluid in the convergence chamber 1213 can be transferred downwardly to the position under the resonance plate 122 through the central aperture 1223.
A process of assembling the fluid control device will be described as follows. Firstly, the outlet plate 11, the second insulation plate 3b, the conducting plate 4, the first insulation plate 3a, the piezoelectric actuator 2 and the base 12 are sequentially stacked on each other from bottom to top. Then, an adhesive 6 is coated on the region between the sidewall 111 of the outlet plate 11 and the accommodation space 113 to prevent the fluid leakage. After the above components are combined together through the adhesive 6, the fluid control device is assembled. The structure of the fluid control device is simple and slim.
The piezoelectric actuator 2 is aligned with the resonance plate 122. Moreover, the piezoelectric actuator 2 comprises a suspension plate 21, a piezoelectric element 22, an outer frame 23 and at least one bracket 24. The resonance plate 122 comprises a movable part 1221 and a fixed part 1222. The movable part 1221 is aligned with the convergence chamber 1213. The fixed part 1222 is fixed on the base 12.
Nowadays, the equipment using the fluid control device is developed toward miniaturization. Consequently, it is necessary to gradually reduce the size of the fluid control device without impairing the output capability (e.g., the output flowrate and the output pressure). However, as the size of the fluid control device is reduced, the output capability is usually impaired. For reducing the size of the fluid control device and maintaining the output capability, the structure of the fluid control device needs to be further improved.
Please refer to FIG. 1 again. As mentioned above, the outlet plate 11, the second insulation plate 3b, the conducting plate 4, the first insulation plate 3a, the piezoelectric actuator 2 and the base 12 are sequentially stacked on each other from bottom to top.
Moreover, the outer frame 23 of the piezoelectric actuator 2 is fixed on the fixed part 1222 of the resonance plate 122 through a glue body 5. That is, the distance between the suspension plate 21 and the resonance plate 122 is substantially equal to the thickness of the glue body 5. As the piezoelectric actuator 2 vibrates, the pressure of the fluid is subjected to a change. Moreover, a portion of the resonance plate 122 and the piezoelectric actuator 2 vibrate at the same frequency. That is, because of the structures of the resonance plate 122 and the base 12, the movable part 1221 facing the convergence chamber 1213 is subjected to curvy vibration. When a voltage is applied to the piezoelectric element 22, the piezoelectric element 22 is stretched or contracted. Consequently, the suspension plate 21 is subjected to the curvy vibration. While the suspension plate 21 is subjected to the curvy vibration, the movable part 1221 of the resonance plate 122 is subjected to vibration. Consequently, the fluid is fed into the at least one inlet 1211 of the base 12. After the fluid is fed into the at least one inlet 1211, the fluid is transferred to the convergence chamber 1213 through the at least one convergence channel 1212. Then, the fluid is transferred to the temporary storage chamber 114 through the central aperture 1223 of the resonance plate 122. Due to the vibration of the suspension plate 21 of the piezoelectric actuator 2 and the resonance effect of the resonance plate 122, the volume of the temporary storage chamber 114 is shrunken. Consequently, the fluid is outputted from the at least one exit 115 of the outlet plate 11. Since the movable part 1221 is vibrated with the piezoelectric actuator 2, the vibration amplitude of the fluid control device is increased. Consequently, although the size of the fluid control device is small, the output pressure and the output flowrate of the fluid control device are still large.
Generally, the piezoelectric actuator 2 is fixed on the base 12 through the glue body 5. For securely fixing the piezoelectric actuator 2 on the base 12, the glue body 5 has to be subjected to a heating and pressing process. However, after the heating and pressing process, the shapes of the suspension plate 21 and the piezoelectric element 22 are changed according to their coefficients of linear expansion (i.e., thermal deformation). Consequently, the distance between the suspension plate 21 and the resonance plate 122 is changed. As known, the distance between the suspension plate 21 and the resonance plate 122 is an important factor influencing the pressure-flowrate characteristics of the fluid control device.
As mentioned above, the pressure-flowrate characteristics of the fluid control device is changed in response to the temperature change. Therefore, there is a need of providing a fluid control device for reducing the change of the pressure-flowrate characteristics in response to the temperature change.